Cable sheath cutting tool



Sept. 8, 1959 K; T. MILLER 2,902,759

CABLE SHEATH CUTTING TOOL Filed Nov. 4, 1958 IN V EN TOR.

United States PatentO 2,902,759 CABLE SHEATH CUTTING TOOL I Kenneth T.Miller, Longmeadow, Mass.

Application November 4, 1958, Serial No. 771,909 4 Claims. (Cl. 30-91)This invention relates to improvements in tools and is directed moreparticularly to a cutting tool for cutting a metal sheath of armoredcable such as a metal sheath of BX cable or BX sheath.

The principal object of the invention is directed to the provision of ahand tool for cutting the sheath of BX cable to facilitate the ready andeasy separation of sections thereof.

BX cable as is well known, is an armored cable, and includes one or moreinsulated wires within a metal sheath. Said sheath is formed by ahelically wound metal strip having one edge of the convolutions thereofoverlapping and interlocked with the underlying edge of adjacentconvolutions. The BX sheath alone may be used as a conduit in wiringinstallations, and when in place wire may be snaked therethrough.

The metal strip forming the BX sheath or conduit is of relatively hardsteel. The cross section of the strip is generally in the shape of an Sfor interlocking purposes, and when arranged as a helix, it is extremelydifficult to cut.

Tools in the form of hack-saws or cutting pliers are well known forcutting BX sheath but same have not been altogether satisfactory.

Such tools require considerable physical effort and time in cutting, theends of the separated sheath sections cut thereby are ragged and sharp,and there is a likelihood of cutting or impairing the wires carriedtherein in the cutting operation.

According to the novel features of the invention, a tool is provided,which is of small size, and is easily and readily operable to cutthrough the sheath in one operation for separating the sections thereof.As one special feature of the invention, the tool embodies a cuttingblade which cuts longitudinally of the BX and entirely across aconvolution of the metal strip to enable sections of the BX to beseparated.

The tool is so constructed that little physical effort is required toprovide the force necessary in cutting the strip of the sheath.

As another feature of the invention, the tool embodies means forclamping the BX for a cutting operation in such a way that, a cuttingblade acts to cut across and through the strip of the sheath so that itis completely and cleanly severed.

As a further feature of the invention, a cutting blade is operated insuch manner as to obviate the likelihood of cutting or injuring the wireor wires within the sheath. Such is accomplished by an elongated bladewhich has a sharpened end which, in a cutting operation, operates in aplane spaced from and parallel to a plane extending through thelongitudinal axis of the BX. Thereby, the cutting edge is directednon-radially of the BX rather than radially so as not to contact wireswithin the BX.

' Various changes and modifications may be made within the spirit andscope of the invention, to be hereinafter shown and described, in itspresently preferred form.

in the drawings:

Fig. 1 is an elevational view of a cutting tool embodying the novelfeatures of the invention, with the clamp plate thereof in its openposition;

ice

Fig. 2 is an end elevational view of the tool shown in Fig. 1, with theclamp plate thereof in clamping position;

Fig. 3 is an elevational view of the rear side of the main plate of thetool;

Fig. 4 is an edge view of the clamp plate of the tool;

Fig. 5 is an edge view of the cutting blade of the tool shown inrelation to a circle representing the cross section of a strip of BX;

Fig. 6 is an elevational view of a length of BX and showing the cut madein the sheath by the tool; and' Fig. 7 is an elevational view of asection of the BX, shown in Fig. 6, which has been removed following acutting operation.

Referring now to the drawings more in detail, the novel features of theinvention will be fully described.

It will be understood that reference to BX will mean the sheath of BX,whether or not a wire or wires are enclosed within the sheath, and itenvisions a sheath without wires for use as a conduit for same.

A main plate is shown at 2 which has an upper extension 4. A clamp plate6 is hingedly connected to the lower edge thereof by means such asleaves 8 and 10 of a hinge 12, shown as secured to the plates 2 and 6respectively as by screws 14 or the like. The hinge parts may be formedon the plates 2 and 6, if desired.

The plates 2 and 6 are provided with elongated semicircular grooves 16and 18 respectively. These are arranged to provide an elongated clampingguideway for the BX when the clamp 6 plate is in the upper clamping PO?sition, as shown in Fig. 2.

A clamp screw 20 has an inner end in a slot 22 of the upper side of theplate 2. A pivot pin 24, on which the screw is pivoted, threadedlyengages the plate 2 inwardly of the slot 22, as shown. A thumb nut 26 isprovided on the screw 20. As the clamp plate 6 is swung to clampingposition, as in Fig. 2, the screw is swung so as to lie in a notch 28 ofthe clamp plate 6. The guideway is formed to received BX of a certaindiameter, and when in the guideway, the thumb nut 26 is turned on theclamp screw 20 to act on the clamp plate 6 so as to clamp the BX I inthe guideway between the plates 2 and 6.

A cutting blade 30 has a lower end portion reciprocable in a guideway32, and is provided with a lower sharpened cutting edge 34. Said blademay be provided with any form of cutting means desired.

As shown in Fig. 6, an outer or head edge 38 of the sheath forming metalstrip, in ,each convolution, overlies, so as to interlock with, anopposite inner outwardly turned edge 40. Each convolution may be said toinclude a bead 38, and a valley 42, the latter. being disposed betweenadjacent beads 38.

The cutting blade 30, in a cutting movement thereof, reciprocates in aplane which is spaced from, and in parallelism with, a plane extendingthrough the. longitudinal axis of the guideway and BX therein. In Fig.5, the longitudinal vertical edge of the cutting blade 30 is shown, andis related to a line 44 representing a plane through the longitudinalaxis of the guideway and BX therein, which BX is represented by dashlines 46.

Such positioning of the cutting blade insures that the wires in thesheath will not be cut, as would be the case were the blade operableradially of the longitudinal axis of the guideway.

The cutting edge 34 of the cutting blade is of such width and is soarranged that, in the cutting operation, the head portion 38 andopposite edge portions of a con-j volution are cut through, as at 44 inFig. 6. In order to cut the convolution all the way across, the nextconvolution is cut as at 46, but one convolution is entirely severed.

With the convolution so severed the section 48 of BX is turnedcounterclockwise relative to section 50 so asto become separatedtherefrom, as in Fig. 7.

To cut the BX strip at the desired location, means is provided forpositioning the BX relative to the cutting blade. Such means includes apin 54 extending through a slot 56 in the. groove 16, of plate 2which-is carried by a leaf spring 58 secured tov the rear sideofplate-2, see Fig. 3; V

The BX is placed in the groove 16 ofplate. 2 with the pin 54 in a valley42 of the BX whereby a convolution to be cuti's positioned correctlyrelative ,to the cutting. edge of the blade 30". a The cutting blade 30is moved downwardly for a cutting operation by a screw 60 having a head,62 rotatable in a T slot of, the blade 30. Said screw 60 threadedlyengagesthe extension 4 of plate 2.

A stop nut 66 is secured in adjusted position on the screw 60 by a setscrew 68. The nut abuts the extension 4 to arrest downward movement ofthe blade so that the cutting edge of the blade will pierce the sheathonly sufiiciently to.cut through a convolution.

The upper edge of the blade 30 abuts the underside 70 of' the extension4 in its upper fully restractedposition.

The clamp plate 6 cannot be swung to its upper clamping position unlessthe blade 30 is in its fully retracted position, as in Fig. 1. Nor canthe clamp plate 6 be swung away from its BX clamping position, unlessthe blade is fully retracted.

A safety member 72 is secured to the outer edge 6' of clamp plate 6 byscrews 74 or the like. Said member has a projecting nose 76 on the outerend-thereof, see Fig. 4. The cutting blade 30 is provided with acomplementary notch 76 in aside thereof, see Fig. 1. With the blade 30in the fully retracted position of Fig. 1', the member 72' of the clampplate 2 will pass through the notch 76 of the blade. as the clamp plate6 is swung to its clamping position. Unless the blade 30 is in theposition shown, the member 72 of plate 6 will abut the blade, and thenotch will not be in the proper aligned position. 1

With the clamp plate 6 in its clamping'position, same cannot be swungaway therefrom unless the blade is in its retracted position, as thenose 76 of member 72 will abut the rear side of the blade 30.

Various changes and modifications may be made in the form of the toolwithout departing from the spirit and. scope of the invention, and it isdesired to secure by Letters Patent of the United States the inventionset forth. in the appended claims.

I claim:

1. A device for cutting a sheath forming strip of BX comprising, a mainplate, a clamp plate hinged'to said main plate and being swingablebetween non-clamping position and BX clamping position relative to saidmain plate, said plates being provided with longitudinal cooperatinggrooves providing a BX clamping gui'deway in the clamping position ofsaid clamp plate, means for moving said clamp plate towards said mainplate in the clamping position thereof, said main plate being providedwith an elongated blade guide opening into the clamping guideway andextending in a direction transversely relative the longitudinal axis ofthe guideway, a blade being reciprocable in the blade guide betweenretracted and cutting positions and having a cutting edge in the cuttingposition thereof for cutting BX in the clamping guideway longitudinallyand transversely of the convolutions thereof, means limitingreciprocation of said blade to cutting position thereof, and meanslimiting reciprocation of said blade to retracted position thereof,said. blade guide being disposed for reciprocation of said blade in aplane spaced outwardly of and parallel to a plane extending through thelongitudinal axis of the clamping guideway.

- 2. A device for cutting a sheath forming strip of BX comprising, amain plate, a clamp plate hinged to said main plate and swingablebetween non-clamping position 2,902,759. V W t and BX clamping positionon said main plate, said plates being provided with longitudinalco-operating grooves providing a BX clamping guideway in clampingposition of said clamp plate, means for moving said clamp plate towardssaid main plate in clamping position thereof, said main plate beingprovided with an elongated blade guide opening into the groove thereofextending in a direction transversely relative to thelongitudinal axisof the BX clamping guideway, a blade reciprocable in the blade guidebetween retracted and cutting positions and having a cutting edge in thecutting position thereof for cutting BX in thev BX clamping guidewaylongitudinally thereof and transversely of the convolutions of the BX,means limiting reciprocation of said blade to cutting positionthereof,means limiting reciprocation of said blade to retracted positionthereof, the blade guide being disposed for reciprocation of: said bladein a plane spaced outward.- ly of and parallel to a plane extendingthrough the longitudinal axis of said clamping guideway, and meanspreventing positioning of said clamp plate in clamping position whensaid blade is in other than the fully retracted position.

3. A device for cutting a sheath forming strip of BX comprising, a mainplate, a clamp plate hinged to said main plate swingable betweennon-clamping position and BX clamping position on said main plate, saidplates being provided with longitudinal co-operating grooves providingaBX clamping guideway in clamping position of said clamp plate, meansfor moving said clamp plate to-' wards said main plate in clampingposition thereof, said main plate being provided with an elongated bladeguide opening into-the groove thereof and extending in a directiontransversely relative to the longitudinal axis of said BX clampingguideway, a blade reciprocable in the blade guide between retracted andcutting positions and having a cutting, edge in cutting position thereofto cut BX in the BX clamping guideway longitudinally thereof andtransversely of the convolutions of-the BX, means limiting reciprocationof said blade to cutting position thereof; means limiting reciprocationof said blade to retracted position thereof, the blade guide beingdisposed for reciprocation of said blade in a plane spaced outwardly ofand parallel to a plane extending through the longitue dinal axisof theBX clamping-guideway, and means pre venting swinging of said clamp platefrom clamping position when said blade is in other than fully retractedposition.

4. A-device for cuttinga sheath forming strip of BX comprising, a mainplate, a clamp plate hinged to said main plate and being swingablebetween non-clamping position and BX clamping" position on said mainplate, said plates being provided with longitudinal co-operating groovesproviding a BX clamping guideway in clamping position of said clampplate, means for moving said clamp plate towards said main plate inclamping position thereof, said main'plate being provided with anelongated blade guide opening into the groove thereof extending in adirection transversely relative to the longitudinal axis of the BXclamping guideway, a blade reciprocable in the blade guide betweenretracted and cutting positions and having a cutting edge in cuttingposition thereof to cut BX in the BX clamping guideway longitudinallythereof and transversely of the convolutions of the BX, means limitingreciprocation of said blade to cutting position thereof, means limitingreciprocation of said blade to retracted position thereof, the bladeguide being disposed for reciprocation of saidblade in a plane spacedoutwardly of and parallel to a plane extending through the longitudinalaxis of the. BX clamping guideway, and means preventing positioning ofsaid clamp plate in clamping position and. preventing swinging of saidclamp plate away from clamping position when said blade is in-other thanfully retracted position.

No references cited.

